A laminate packaging material using a metal foil having good barrier characteristics for oxygen or moisture to prevent chemical change, deterioration, and corrosion, etc., of contents of foods, pharmaceutical products, etc., in the packaging material, has been widely known.
On the other hand, with the reduction in size and weight of various electronic equipment such as OA devices such as personal computers, mobiles phones, game machines, headphone stereos, electronic notebooks, etc., as a battery for a power supplying unit, lithium ion polymer secondary batteries have become increasingly used from the view point of the reduction in size and weight. In a lithium ion polymer secondary battery, when the electrolyte in the battery reacts with water to thereby form a hydrofluoric acid, the performance of the battery may deteriorate or leakage may occur due to corrosion of the aluminum foil. Therefore, as a material for use in a case (accommodation case) for lithium ion polymer secondary batteries, a laminate packaging material high in sealing performance using a metal foil excellent in moisture barrier properties has become used.
As a material for use in a case for lithium ion polymer secondary batteries (packaging material), a laminate packaging material is used, in which an outer layer made of a heat resistant resin film, an intermediate layer made of an aluminum foil as a moisture barrier layer, and an inner layer made of a polyolefin film for sealing polymer electrolytes as contents are integrally laminated.
The aforementioned laminate packaging material is formed into a three-dimensional cuboid shape, etc., by bulging or deep drawing to increase the capacity for filling polymer electrolytes as much as possible, to thereby produce a battery case.
As a production method of the laminate packaging material, the following methods are known. According to one of the methods, in a laminate forming an emboss type exterior body constituted by at least a base material layer, an adhesive layer, a chemical conversion treatment layer, an aluminum, a chemical conversion treatment layer, an acid modified PP film layer, an extruded resin layer, and an innermost layer, both surfaces of the aluminum is subjected to a chemical conversion treatment and the base material layer is adhered to one of the surfaces of the aluminum by a dry lamination method, then an acid modified PP is applied to the other chemical conversion treatment surface and baked thereto, and then the acid modified PP surface and the innermost layer (cast PP) are laminated with an extruded resin by a sandwich lamination method (see Patent Document 1). According to the other method, in a lamination forming an emboss type exterior body constituted by at least a base material layer, an adhesive layer, a chemical conversion treatment layer, an aluminum, a chemical conversion treatment layer, an acid modified PP film layer, an extruded resin layer, and an innermost layer, one surface of the aluminum is subjected to a chemical conversion treatment, and the base material layer is adhered to the chemical conversion treatment surface by a dry lamination method, then the non-processed surface of the aluminum is subjected to a chemical conversion treatment, an acid modified PP is applied to the chemical conversion treatment surface and baked thereto, and then the acid modified PP surface and the innermost layer (cast PP) are laminated with an extruded resin by a sandwich lamination method (see Patent Document 1).
Furthermore, other methods are also known. According to one of the methods, in a laminate forming an emboss type exterior body constituted by at least a base material layer, an adhesive layer, a chemical conversion treatment layer, an aluminum, a chemical conversion treatment layer, an acid modified PP film layer, and an innermost layer, both surfaces of the aluminum are subjected to a chemical conversion treatment, one of the chemical conversion treatment surfaces and the base material are laminated by a dry lamination method, then an acid modified PP is applied to the other chemical conversion treatment surface and baked thereto, and then the innermost layer is laminated to the acid modified PP surface (see Patent Document 2). According to the other method, in a laminate forming an emboss type exterior body constituted by at least a base material layer, an adhesive layer, a chemical conversion treatment layer, an aluminum, a chemical conversion treatment layer, an acid modified PP film layer, and an innermost layer, one surface of the aluminum is subjected to a chemical conversion treatment, the chemical conversion treatment and the base material are laminated by a dry lamination method, then the other surface of the aluminum is subjected to a chemical conversion treatment and then an acid modified PP is applied and baked thereto, thereafter a cast polypropylene is laminated on the acid modified PP surface by a heat laminating method (see Patent Document 2).
Another production method is also known, in which an organosol having an acid-modified polyolefin as a solid content is applied to a chromic chemical conversion treatment film surface of a metal foil made of a metal foil main body and a chromic chemical conversion treatment film formed by subjecting at least one surface of the metal foil main body to a chromate treatment, then the organosol is dried to form an adhesive film, thereafter an acid-modified polyolefin film of the same kind as the acid-modified polyolefin in the organosol is pressure-bonded to the adhesive film to adhere the metal foil and the acid-modified polyolefin film to thereby make the acid-modified polyolefin film as a heat-sealing layer (see Patent Document 3.)